I. Field of the Invention
The invention relates to wireless communication systems. More particularly, the invention relates to wireless networks.
II. Description of the Related Art
Data networks which provide wired connectivity to a set of users are a vital part of the business, academic and consumer environment today. For example, one of the largest data networks in the world is the Internet. In addition to the Internet, many organizations have private networks to which access is limited to a select number of users. For example, a corporation may have an internal data network which interconnects its computers, servers, dumb terminals, printers, inventories and test equipment using a wired Ethernet topology.
When a system user leaves his desk, he often does not wish to lose his connection to the data network. If the user attends a meeting within his organization, he may wish to bring his computer and print out documents on a local printer. He may also wish to maintain connectivity to the data network while moving between his office and the meeting so that he may, for example, continue to download or print a large file, maintain contact with colleagues, or simply avoid re-initiating the connection when he reaches his final destination. All of the functions can be supported through the use of a distributed wireless data network.
FIG. 1 is a block diagram of a distributed wireless data network architecture. In FIG. 1, a series of network access points 12A-12N are distributed throughout a service area. In a typical configuration, each network access point 12 has one or more antennas which provide a corresponding coverage area which abuts one or more coverage areas of other network access points 12 so as to provide a contiguous service area. In the configuration shown in FIG. 1, the network access points 12A-12N may provide continuous coverage for a campus of buildings occupied by a single entity.
In the distributed architecture of FIG. 1, each of the network access points 12A-12N is a peer to the others and no single network access point 12 is designated as a general controller. The network access points 12A-12N are interconnected by a packet router 14. The packet router 14 also interconnects the network access points 12A-12N to an external packet switched network 16 which may be another private network or public network such as the Internet. The packet router 14 can be an off-the-shelf product which operates according to an industry standard protocol suite. For example, the packet router 14 may be a CISCO 4700 packet router marketed by Cisco Systems, Inc. of San Jose, Calif., USA. The industry standard packet router 14 operates according to the Internet protocol (IP) suite. In such a configuration, individual entities within each network access point 12 are assigned a unique IP address and, when an entity within a network access point 12 wishes to communicate with another entity within the other network access points 12A-12N or with an entity coupled to the packet switched network 16, it passes an IP packet to the packet router 14 designating the destination IP address. In addition to the network access points 12A-12N, other entities may be directly wired to the packet router 14 such as printers, computers, test equipment, servers, dumb terminals or any other manner of equipment with data capabilities. These devices are also assigned IP addresses.
Each network access point 12 comprises one or more landside wireless modems which may provide communication with a user terminal 18. Each user terminal 18 comprises a remote unit wireless modem. For discussion purposes, we assume that the wireless modems within the network access points 12A-12N and user terminal 18 provide a physical layer in accordance with the modulation and multiple access techniques described in the TIA/EIA Interim Standard entitled xe2x80x9cMobile Stationxe2x80x94Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,xe2x80x9d TIA/EIA/IS-95, and its progeny (collectively referred to here in as IS-95), the contents of which are also incorporated herein by reference or similar subsequent standard. However, the general principles can be applied to many wireless data systems which provide a physical layer interface capable of true mobility.
In FIG. 1, each network access point 12 is coupled with control point capabilities. The control point functionality provides mobility management to the system. The control point functionality executes a plurality of functions such as management of the radio link layer, the signaling protocol and data link layer over the wireless link.
In a typical data system, when a user terminal 18 initially establishes communication with the network, it uses a mobile station identifier (MSID). In one embodiment, the user terminal 18 determines the MSID based upon the network access point""s electronic serial number or the mobile identification number or other permanent address associated with the user terminal 18. Alternatively, for increased privacy, the user terminal 18 may select a random number. The user terminal 18 sends an access message to the network access point 12 using the MSID. Using the MSID to identify the user terminal 18, the network access point 12 and user terminal 18 exchange a series of messages to establish a connection. Once an established, encrypted connection is available, the actual mobile station identification can be transferred to the network access point 12 if a random or other nonfully descriptive MSID has been used.
A temporary mobile station identifier (TMSI) can also be use to identify the user terminal 18. The TMSI is considered temporary in that it changes from session to session. A new TMSI may be selected when the user terminal 18 enters another system in which the new network access point is not directly coupled to the originating network access point 12. Also, if power is removed from the user terminal 18 and then reapplied, a new TMSI may be selected.
The originating network access point 12 in which communication is initially established retains in memory the characteristics of the user terminal 18 as well as the current state of the connection. If the user terminal 18 moves to the coverage area of another network access point 12, it uses the TMSI to identify itself to the network access point 12. The new network access point 12 accesses a system memory unit 20 in which the originating network access point 12 is identified as associated with the TMSI. The new network access point 12 receives data packets from the user terminal 18 and forwards them to the indicated originating network access point 12 using the IP address specified in the system memory unit 20.
The process of accessing the system memory unit 20 and managing a centralized pool of TMSIs is cumbersome and consumes system resources. In addition, the process introduces a single point of failure in that a failure of the system memory unit 20 can disable the entire system.
Thus, it will be appreciated that there is a need in the art for a method and system of user terminal identification which is more efficient.
A first network access point receives a first wireless link message from a first user terminal. The first wireless link message identifies the first user terminal. The first network access point or other system entity assigns an IP address to the first user terminal for use as a temporary mobile station identifier. The first network access point or other system entity installs a route for the IP address to a controller which controls communication with the user terminal. In one embodiment, the controller is within the first network access point. The first network access point forwards a wireless link message to the user terminal specifying the IP address. The first or a second network access point receives another wireless link message from the first user terminal in which the first user terminal is identified with the IP address. The first or second network access point parses the message to determine the IP address and creates at least one standard IP packet designating the IP address specified in the message. The first or second network access point forwards the message to a router which routes the packet according to the IP address.
A system for providing wireless service includes a packet router and a first network access point. The first network access point has a first coverage area. The first network access point is configured to receive wireless link signals from a user terminal within the first coverage area and to establish a route within the packet router for an IP address which corresponds to control functionality within the first network access point. The first network access point is further configured to receive messages from the user terminal identifying itself with the IP address. In one embodiment, the system comprises a second network access point. The second network access point is configured to receive wireless link messages from the user terminal within a second coverage area, to parse the wireless link message to determine the IP address and to create a standard IP packet designating the IP address. The second network access point passes the standard IP packet to the packet router which forwards it according to the established route.